pcsx2-counters: Revert to older VRender/VBlank timings

This fixes timing issues in Dynasty Warriors 3 Xtreme Legends
(fake save corruption), Jak II (random speedup issues) and Shadow of
Rome (FMV audio issues).

Also update the comments since a lot of them refer to past revisions of
the code.

pcsx2/Counters.cpp

@@ -196,26 +196,24 @@ static void vSyncInfoCalc(vSyncTimingInfo* info, Fixed100 framesPerSecond, u32 s
 {
 	// I use fixed point math here to have strict control over rounding errors. --air
 
-	// NOTE: mgs3 likes a /4 vsync, but many games prefer /2.  This seems to indicate a
-	// problem in the counters vsync gates somewhere.
-
 	u64 Frame = ((u64)PS2CLK * 1000000ULL) / (framesPerSecond * 100).ToIntRounded();
-	u64 HalfFrame = Frame / 2;
+	const u64 Scanline = Frame / scansPerFrame;
 
-	// One test we have shows that VBlank lasts for ~22 HBlanks, another we have show that is the time it's off.
-	// There exists a game (Legendz Gekitou! Saga Battle) Which runs REALLY slowly if VBlank is ~22 HBlanks, so the other test wins.
-
-	u64 Blank = HalfFrame / 2; // PAL VBlank Period is off for roughly 22 HSyncs
-
-	//I would have suspected this to be Frame - Blank, but that seems to completely freak it out
-	//and the test results are completely wrong. It seems 100% the same as the PS2 test on this,
-	//So let's roll with it :P
-	u64 Render = HalfFrame - Blank;	// so use the half-frame value for these...
+	// There are two renders and blanks per frame. This matches the PS2 test results.
+	// The PAL and NTSC VBlank periods respectively lasts for approximately 22 and 26 scanlines.
+	// An older test suggests that these periods are actually the periods that VBlank is off, but
+	// Legendz Gekitou! Saga Battle runs very slowly if the VBlank period is inverted.
+	// Some of the more timing sensitive games and their symptoms when things aren't right:
+	// Dynasty Warriors 3 Xtreme Legends - fake save corruption when loading save
+	// Jak II - random speedups
+	// Shadow of Rome - FMV audio issues
+	const u64 HalfFrame = Frame / 2;
+	const u64 Blank = Scanline * (gsVideoMode == GS_VideoMode::NTSC ? 26 : 22);
+	const u64 Render = HalfFrame - Blank;
 
 	// Important!  The hRender/hBlank timers should be 50/50 for best results.
 	//  (this appears to be what the real EE's timing crystal does anyway)
 
-	u64 Scanline = Frame / scansPerFrame;
 	u64 hBlank = Scanline / 2;
 	u64 hRender = Scanline - hBlank;